In a redundant arrays of inexpensive disks (RAID) apparatus, for example, data is transmitted through cables using various buses. Most of buses (cable buses) used for cable transmissions are designed in accordance with standards that are stipulated for cable transmissions. Hence, devices connected through a cable can determine their own locations in the connections by exchanging Slot IDs, for example.
On the contrary, only a limited number multi-purpose central processing units (CPUs) directly support cable buses. Thus, a controller device that converts the Peripheral Component Interconnect Express (PCIe) supported by multi-purpose CPUs to cable buses is provided to a controller module (CM).
In such conventional RAID apparatuses, simply providing a controller device that carries out the above conversion from the PCIe into cable buses to a CM increases the production costs and results in a reduction in the performance.
To avoid such issues, direct cabling of PCIe is considered, without providing a controller device.    Patent Document1: Japanese Laid-Open Patent Publication No. 2009-104351    Patent Document2: Japanese Laid-Open Patent Publication No. 8-153017
However, for direct cabling between PCIe devices, it is required to determine whether devices are properly connected.